window.addEventListener('load', function () {
    // 头部
    let nav_list = document.querySelectorAll('#navs li a');
    // 遍历li
    nav_list.forEach(function (v) {
        v.addEventListener('mouseover', function () {
            nav_list.forEach(function (j) {
                j.className = ''
            })
            v.className = 'active'
        });
        v.addEventListener('mouseout', function () {
            v.className = ""
        })

    })
})
